Laundry drying machine



Nov. 11, 1941.

B. LINDBERG LAUNDRY DRYING MACHINE Filed March 8, 1940 2 Sheets-Sheet lNOV. 11, 1941. LINDBERG LAUNDRY DRYING MACHINE Flled March 8, 1940 2Sheets-Sheet 2 Patented Nov. 11, 1941 LAUNDRY DRYING MACHINE BernhardLindberg, Chicago, 111. Application March 8, 1940, Serial No. 322,925

9 Claims.

The object of the present invention is to produce a simple, novel andefficient machine or apparatus for drying laundry after it has beenwashed.

Drying machines have heretofore been constructed with rotatable drumshaving perforated walls, each drum being enclosed in a casing, and

means being provided for drawing heated air through the casings and moreor less through the drums. Such air as passes through a drum picks upmoisture from the laundry, but it also picks up lint much of whichremains in the casing and in time stops up the passages between the drumand the walls of the casing. Therefore, in the old type of machine, handholes must be provided through which the massed lint may be removed fromtime to time. Also, since the heated air is confined solely by thecasing, the latter becomes hot, thereby causing a waste of heat throughconvection and radiation from the casing. The fact that the casing ishot is also objectionable from the standpoint 0f,the convenience andcomfort or even safety of the operators who, unless they always exercisegreat care, are apt to receive burns through contact with the casing.

Viewed in one of its aspects, the present invention may be said to havefor its object to produce a simple and novel drier of the rotatable drumtype which eliminates the objectionable characteristics of the olderstyle just mentioned.

In carrying out my invention, instead of perforating the walls of thedrum in which the laundry is tumbled, I make them solid and provide thedrum with a definite inlet and definite outlet forthe drying air. Also,instead of attempting to draw heated air through the drum, I force itinto the drum and permit it to escape only through the outlet providedtherefor. Consequently, only the outlet need be screened, and, becauseall of the moisture-laden air must flow through this screen. a greatenough force is exerted upon any lint carried along with the stream ofair to carry it through the screen; whereby clogging by the lint isprevented. 'Ine air which is forced into the drum may first be drawnfrom the outside into the casing and past the drum, thereby keeping thewalls of the casing cool and giving to the incoming air a. preliminaryheating through contact with the drum.

The more or less warm air is then heated to the desired temperature andforced directly into the drum and, therefore, its heat units cannot bewasted in the raising of the temperature of the walls of the casing orin the heating of the motor and other mechanism located within theeasing for rotating the drum and forcing the air into the drum.

In order that even the door in the casing through which the laundry isinserted and removed may be cooled by the air that is afterwards used indrying the laundry, the end of the drum adjacent to that door must bespaced apart from the door in the casing and must therefore be providedwith its own door. A further object of the present invention is toproduce a simple and novel compound closure for both a door opening inthe casing and a door opening in the drum, whereby both the casing andthe drum may be opened and closed by an action on the part of anoperator that is no different from the act of opening and closing anysingle door.

The various features of novelty whereby my invention is characterizedwill hereinafter be pointed out with particularity in the claims; but,for a full understanding of my invention and of its objects andadvantages, reference may be had to the following detailed descriptiontaken in connection with the accompanying drawings, wherein:

Figure 1. is a vertical section through a drying apparatus embodying thepresent invention, the plane of the section being at right angles to theaxis of the drum; Fig. 2 is a section taken on line 2-2 of Fig. 1,showing the door closed; Fig. 3 is a. section on a much larger scale, online 3-3 of Fig. 2, showing a part of the compound door; Fig. 4 is afront view of the drier on a greatly reduced scale; Fig. 5 is a viewsimilar to Fig. 2, buton a smaller scale and including only the drum andthe upper part of the casing, showing a modification.

Referring to the drawings, l represents a drum of any desired length anddiameter, comprising a cylindrical shell 2 composed of a sheet metal orlight plate material, together with the end walls 3 and 4. The drum isrotatably supported, with its axis horizontal, in a suitable casing 5.In the arrangement shown, the drum rests on two pairs of rollers 6 whichmay conveniently be composed of hard rubber. The rear wall of the drumcontains a rather large central opening 1 with which registers asleeve-like hub 8 projecting rearwardly from thiswall. The hub fitsrotatably into the inner end of a stationary,

open-ended sleeve 9 extending through and fixed in the rear wall of thecasing. The opening 1, together with the hub and the sleeve 9, form theoutlet from the interior of the drum to the fastened to the hub on thedrum. The outlet from the rear end of the drum is coveredby a strainerwhich may conveniently be a wire screen l2 formed into a frusto-conicaldish; the large diameter of the dish being about equal to that of theopening I, and the end of larger diameter being fastened to the rearwall of the drum.

In the front end wall of the drum is a large door opening adapted to beclosed by a" pan-' shaped door or cover I; both the door opening and thedoor or cover being round. The front wall of the casing is provided witha circular door opening registering with but larger in diameter than theopening in the drum. The door opening in the casing is closed by meansof a door l5 which may be similar to the door M; the door l5 beinghinged to the front wall of the casing at one side of the door opening,as :indicated at It, and being adapted to be secured in its closedposition by a suitable latch I'I arranged diametrically opposite thehinge. In accordance with the present invention, the two doors areconnected together in such a manner that they may be opened and closedtogether by a single movement; the door for the drum closing in advanceof the other door, however, and being held closed by a yieldablepressure just before and also after the outer door reaches its seat.Also, the two doors are connected together so that the inner door mayrevolve with the drum while the outer door remains stationary. Theprinciple of the mounting for the inner door on the outer door is illustrated in Fig. 3. It will be seen that the outer door has on the rearside, at the center, a frustoconical sleeve I8, whereas the inner doorhas fixed on the outer side thereof a frusto-conical projection l9 whoselarger diameter is smaller than the smaller internal diameter of thesleeve l8; the angles of the conical surfaces being alike so that'whenthe member I9 is inserted, small end first, through the large end of thesleeve, it may be moved ahead until the greater portion thereof projectsbeyond the small end of the sleeve, but no farther. The member I9 ismade dish-shaped and is provided in the center of the dish with a socketcontaining an anti-friction thrust bearing 2|. One element of thisthrust bearing is attached to an end of a coil spring 22 whose other endengages with the inner face of the outer door; the spring being of suchlength that it is under compression even when the part H! has beenprojected out through the small end of the sleeve l8 as far as it willgo. The parts are so proportioned that after the inner door has; beenclosed, the outer door cannot gain its seat until the spring has beencompressed and the member 19 has receded moreor less into the interiorof the sleeve l8, as shown in Fig. 3. Consequently, as long as the outerdoor is closed, the spring is exerting a constant pressure against theinner door. Furthermore, the' telescoped portions of the sleeve and themember I! do not touch each other and the member I! may rotate with thedrum without being retarded by any frictional coaction between thesleeve l8 and the member IS; the only negligible resistance to rotationof the inner door being that offered by the anti-friction thrustbearing. As soon as the outer door is swung open, however, the springforces the inner rear.

door rearwardly until the frusto-conical member It fits snugly againstthe surrounding rear end of the sleeve l8; thus temporarily locking theinner door in a fixed position on the outer door to cause the two doorsto act as a single rigid structure at all times except when the innerdoor contacts the drum. h

In the bottom of the casing, below the drum, is a blower 24, thedischarge side of which is connected to a conduit 25 that extendsupwardly and through the lower side of the stationary sleeve 9. At theaxis of this sleeve the conduit is bent laterally so as to extendforwardly. in the casing through the center of the tubular hub 8 on thedrum. The forward end of the horizontal section of the conduit is openand terminates near the vertical central portion of the strainer orscreen l2. The inlet side of the'blower is connected to a funnel-likeintake 21 containing a suitable heating element 28. In the rear wall ofthe casing, near the top, is a window which is preferably covered by awire screen 23 or other strainer through P which air may pass.

the shaft of the motor 30 and over a sprocket wheel ,33 surrounding andfixed to the hub 8 on the drum.

Assuming that the compound door has been closed and that the motors arerunning, the drum will be rotated and air will be driven by the blowerinto the center of the drum from the The only way that air can escapefrom the drum is through the screen or strainer I2 and through thetubular members 8 and 9 to the exterior of the casing. The heater beingin operation, air for the blower is taken in through the window at thetop of thecasing and flows down around the drum and into the intake forthe blower. a short time, this incoming air, flowing over the surfacesthereof, absorbs heat and therefrom reaches the heater in the blowerintake in a warm condition. The incoming air forms a protective liningfor the casing, preventing it from becoming heated; this beingaccomplished by the cooling action of the outer strata of the airflowing past the interior surfaces of the casing walls and through theabsorption by the air of heat energy that might otherwise pass from thewalls of the drum to the walls of the casing. As a result, the casingwalls never become hot, and therefore no heat energy is wasted in thisway, and neither are the attendants subjected to the annoyance andperhaps danger through touching a hot casing.

In order to make the apparatus eifective, it is necessary that thecontents of the drum be lifted and then dropped again as the drumrotates or, in other words, he tumbled. This may conveniently beaccomplished by providing deep, longitudinal ribs 34 distributed alongthe inner surface of the cylindrical wall of the casing. With thisarrangement, as the drum revolves, one rib after another serves as alifting step for laundry engaged therewith, causing the same to beraised above the level of the axis of the drum and then to drop down.This so-called tumbling action effects a removal of the wrinkles in thewet fabrics and, also, opens or spreads the individual Since the drumitself becomes warm in pieces so that they will present large surfacesto the blasts ofhot air entering the drum.

I have found that in order to secure the best results, the discharge ornozzle end of the blower conduit should extend a substantial distanceinto the drum. Possibly the eflect of this is to permit the strainer I!to act as a baflle upon which pieces of laundry may drop and thus befirst subjected to the action of the moisturebearing air that is tryingto escape from the drum, and then be allowed to pass directly across thestream of fresh, heated air entering the drum.

In the event that a laundry handles many small lots which should be keptseparated from each other, and none of which could be efficientlytreated individually in a large drum, the drum may be divided intocompartments by longitudinal partitions. Thus, in Fig. 5, I have showntwo wire mesh partitions 35 and 36 each extending diametrically acrossthe interior of the drum from one end to the other, and the twopartitions being arranged at right angles to each other so as to dividecompartments, all of which are accessible through the single dooropening in the front end of the drum.

The moisture-laden air that travels rearwardly through the stationaryoutlet sleeve 9 may be carried to any desired point before being disacharged into the surrounding atmosphere. Usually, it will be suflicientto fasten the mouth of a bag (not shown) over the outer end of themember 9, thereby collecting the lint and preventing it from filling theair in the room in which the apparatus may be located.

While I have illustrated and described with particularity only thesingle preferred form of my invention, with a slight modification, I donot desiie to be limited to the exact structural details thusillustrated and described; but intend to cover all forms andarrangements which come within the definitions of my inventionconstituting the appended claims.

I claim:

1. In a laundry drying machine, a casing, a drum rotatably mounted inthe latter and having a large outlet leading to the exterior of thecasing, said drum having a door opening through which laundry isinserted and removed. a door for said door opening, the drum beingconstructed to shut off direct communication between the interior of thedrum and the surrounding space within the casing, a heater in the bottomof the casing, and means to cause air to flow into the top of thecasing, between the exterior of the drum and the surrounding casing,then past the heater and then into the drum.

2. In a laundry machine, a casing, a drum mounted in the latter forrotation about a horizontal axis and having at one end a large centraloutlet leading to the exterior of the casing, said drum having a dooropening through which laundry is inserted and removed, a (iuOI for saiddoor opening, the drum being constructed to shut oil directcommunication between the interior of the drum and the surrounding spacewithin the casing, the casing having an air inlet at the top, a blowerin the bottom of the casing, a heater associated with the inlet to theblower, and a discharge conduit leading from the blower through said outet and into the interior of the drum.

3. In a laundry machine, a casing, a drum mounted in the latter forrotation about a horizontal axis and having at one end a large centraloutlet leading to the exterior oi the casing, said drum having a dooropening through which laundry is inserted and removed, a door-for saiddoor opening, the drum being constructed to shut oif directcommunication between the interior of the drum and the surrounding spacewithin the casing, the casing having an air inlet at the top, a blowerin the bottom of the casing, a heater associated with the inlet to theblower, a discharge conduit leading from the blower through said outletand into the interior or the drum, and a perforated cover over the innerend of said outlet.

the interior of the drum into four 4. In a laundry machine, a casing, adrum mounted in the latter for rotation about a horizontal axis andhaving at one end a large central outlet leading to the exterior of thecasing, said drum having a door opening through which laundry isinserted and removed, a door for said door opening, the drum beingconstructed to shut 01! direct communication between the interior of thedrum and the surrounding space within the casing, the casing having anair inlet at the top, a blower in the bottom of the casing, a heaterassociated with the inlet to the blower, a discharge conduit leadingfrom the blower through said outlet and into the interior of the drum,and a dish-shaped wire screen within and fix'ed to the drum over saidoutlet and the adjacent end of said conduit.

5. In a laundry machine, a casing, a drum mounted in the latter forrotation about a horizontal axis and having in one end a large centraloutlet leading to the exterior of the casing, said drum, having a dooropening through which laundry is inserted and removed, a door for saiddoor opening, the drum being constructed to shut off directcommunication between the interior of the drum and the surrounding spacewithin the casing, meansin the drum to lift the contents of the latterand to permit them to drop as the drum revolves, the casing having anair inlet at the top, a blower in the bottom of the casing, a heaterassociated with the inlet to the blower, a discharge conduit leadingfrom the blower through said outlet and into the interior of the drum,and a perforated cover over the inner end of said outlet.

6. In a laundry machine, a casing, a drum mounted in the latter forrotation about a horizontal axis and having in one end a large centraloutlet leading to the exterior of the casing, a door in the drum, thewalls of the drum being imperforate except for the outlet and the dooropening, the casing having an air inlet at the top, a

blower in the bottom of the casing, a heater associated with the inletto the blower, a discharge conduit extending from the blower throughsaid outlet and. a considerable distance into the interior of the drum,and a dish-shaped strainer within and fixed to the drum over said outletand the adjacent end of said conduit.

7. In a laundry drying machine, a casing, a drum mounted in the latterhorizontal axis and having in one end a large open outlet leading to theexterior of the casing and in its other end a door opening, the walls ofthe drum being imperforate except for the outlet and the door opening, adoor for said door opening, a heater in the bottom of the casing, andmeans to cause air to flow into the top of the casing, between theexterior of the drum and the surrounding casing, past the heater andinto.

the drum.

8. In a laundry machine, a casing, a drum 7 for rotation about a'being'imperforate except for the outlet and the 5 door opening, alongitudinal perforated partition extending across the interior of thedrum, the casing having an air inlet at the top, a blower in the bottomof the casing, a heater associated with the inlet to the blower, and adischarge con- 10 duit leading from the blower through said outlet andinto the interiorofthedrum.

9. In a laundry drying machine, a casing, a-

horizontal drum rotatably mounted in the casing with one end spaced ashort distance from a wall 15 of the casing, said end oithe drum andsaidwall of the casing having registering door openings, a door for theopening in said wall, a door for the drum, 2. irusto-conical sleevefastened on the inner side of the door for the casing with its smallerend farthest from that door, a frustoconical boss fastened on the doorfor the drum positioned partially in and partially out of said sleeve,and a-spring within the sleeve loosely enga'ged with and exerting apressure against the boss to force the doors apart, the parts being soproportioned that the boss lies far enough back in the sleeve, when thedoors are closed, to be out of contact with the sleeve.

LINDBERG.

